1. Field of the Invention
The invention relates to interconnects, and in particular to interconnects that for improve electro-migration properties in integrated circuits.
2. Description of the Related Art
Integrated circuits may include multiple semiconductor components such as, field effect transistors (FET's) or bipolar transistors (BPT's), that are driven by means of interconnects or interconnect structures. In large scale integrated circuits, multiple interconnect planes, or metallization planes, may be provided. The interconnect planes are isolated from one another by insulating layers. The interconnect planes are connected to one another by electrically conductive connection elements, also referred to as “vias”. The connection elements may be arranged in a grid perpendicular to the interconnects.
FIG. 1 shows a conventional interconnect connection structure where a first interconnect M1, or first metallization layer, is connected to an overlying second interconnect by an array of nine connection elements or vias V. FIG. 2 shows a sectional view A-A of the interconnect connection structure of FIG. 1. The first interconnect M1 is situated on a carrier layer 1, such as a substrate, and is correspondingly patterned. An insulation layer D is formed on a surface of the first interconnect M1 and the carrier layer 1. Contact holes to the first interconnect M1 are formed in the insulation layer D, and electrically conductive material is subsequently filled in to realize the connection elements or contact vias V. A second interconnect, or second metallization layer M2, is situated on the surface of the insulation layer D and the connection elements V, and is electrically connected to the first interconnect M1 by means of the connection elements V.
Interconnect structures allow a current flow through the interconnect structure. A maximum possible current density, (i.e., current per interconnect cross section), in accordance with Black's law, is directly proportional to the lifetime of the structure. The maximum current density and lifetime may be determined during a technology qualification or testing. In a product design, any section or part of a metallization or an interconnect has a maximum current density that is not to be exceeded permitted.
An interconnect connection structure may constitute a weak point in interconnect structures due to a barrier function with regard to a material transport, such as electro-migration phenomena. Wider interconnects may be used, taking up additional area in a product or circuit layout. Where technology does not support current density design needs, the product or the semiconductor component may not be produced.
Electro-migration properties may be improved to make a current uniform over an interconnect width, by introducing slots filled with a dielectric and having different lengths into the interconnects. However, such connection structures are very complex and costly.
Therefore, there is a need for a cost-effective interconnect connection that realizes improved electro-migration properties, and thus, increased current-carrying capacities of the interconnects.